Field of the Invention
This invention relates to a jig for guiding a routing tool or the like for cutting the ends of elongate workpieces, and in particular wooden mouldings, to enable accurate joints to be made.
Description of the Prior Art
Skirting boards, picture rails, dado rails, window frame sections and the like are often made with a decorative cross section. When fixing such features around a room or constructing a frame from such sections, it can be difficult to produce neat and accurate joints at corners, with the two profiled sections mating accurately and without a gap between them. If one attempts to cut a 45° mitre joint, it will often be found that the corner in which the two sections meet is not an exact right angle, particularly in an old building. This can result in a gap between the ends of the mating sections, and it can be difficult to trim either cut end to the correct angle.
Best practice therefore is to cut the end of one profiled section to match the cross section of the other. This can be done with a router or similar tool, but an accurate guide or template is needed to enable such cuts to be made accurately and reproducibly. At present such templates can only be produced by expensive factory-based equipment and there is also a need for a portable and adaptable device that can be set up on site to reproduce any desired section. WO2008/029127, the disclosure of which is incorporated herein by reference, describes a router jig on which is mounted a profiling comb, comprising a set of thin parallel plates, each being individually and reversibly slidable in one direction relative to the others, with means for locking the plates relative to one another, whereby a set of plates can be pushed against a section of the moulding to be matched, each said plate being pushed into abutment with the profile so that the abutting ends of the plates together form a cam surface in the shape of a cross section of the moulding, and can be locked in that configuration, the jig also having a slide or other moveable mounting on which a cutting tool can be mounted to follow a path defined by the cam surface to cut an end of a section to match the profile. The jig illustrated comprises a workpiece support with a tool support comprising a frame or platform supported above it, for example on pillars, the comb being mounted on the tool support together with the cutting tool slide and preferably also clamping means for the section to be cut or for the section whose profile is to be reproduced. The jig described in this document can cut one end of a profiled workpiece so that it can accurately match the cross section of a workpiece with which it is to be mated substantially at right angles, enabling and professional-looking joint to be made.
The present inventor has looked for ways to improve the known type of jig described above, in particular to make it easier to use and also to enable it to profile a wider range of workpieces, notably including crown mouldings used to embellish the joints between walls and ceilings. It has not hitherto been possible to profile such mouldings using a router.